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Researchers at Fudan University in Shanghai, China are proposing a method which could lead to the first soft, tunable metamaterial, the key ingredient in building an invisibility device. "The fluid proposed by Ji-Ping Huang of Fudan University in Shanghai, China, and colleagues, contains magnetite balls 10 nanometers in diameter, coated with a 5-nanometer-thick layer of silver, possibly with polymer chains attached to keep them from clumping. In the absence of a magnetic field, such nanoparticles would simply float around in the water, but if a field were introduced, the particles would self-assemble into chains whose lengths depend on the strength of the field, and which can also attract one another to form thicker columns. The chains and columns would lie along the direction of the magnetic field. If they were oriented vertically in a pool of water, light striking the surface would refract negatively – bent in way that no natural material can manage."

Maybe sensational reporting of just about everything (eg the LHC) is causing the public's lack of affinity for science. All they see is hundreds of 'broken promises' made by the media about fantastic whizz-bang technologies that the research they are reporting on isn't even working towards.

An internal power source must obey the laws of thermodynamics and thus would cause the craft as a whole to be an infrared emitter. We are very good at detecting infrared light which would defeat most cloaking devices including this one.

Actually no, just the fact of being invisible. In order to be invisible you have to refract all the light that would normally hit the object being invisible, meaning it would be in absolute dark. You could be invisible in the girls (or guys for the/.ers so persueded) shower room, but you couldn't see a blasted thing. Any lighted object within the cloak could also, possibly, leak out giving away your concealment. So even IF (a big if) the use of, say, an infrared camera, would allow you to see through the cloak, the use of it would give you away as the light from the screen/goggles could give you away. Not to mention you would have to use some containment of the matrix supporting the nano-particles (the fluid). A magnetic field strong enough to suspend water (i'm not even sure if there is such) would likely throw off the magnetic particles, so in turn you would need to have some sort of containment beyond the aqueous sphere. Think fishbowl. The container (fishbowl) in turn, would be visible being outside the sphere of invisibility. So you would see this great 'empty' spherical container just sitting there. Which, logic denotes, means the rat got out, elliciting chaos and panic in said locker room.

This is just one of the great physics problems that everyone has to come up with an 'answer' to, and get their jollies just from doing that. If you wanna be invisible in the girls shower room the best bet is still a very small drill and a pinhole camera, as any A/V geek knows all too well.

It would work "optically" if the Invisibility Cloak was made out of vegetable oil and you were made of Pyrex...

Vegetable oil and Pyrex has the same refractive index...

* put a small Pyrex jar into a larger one and then fill the smaller (inner) jar with vegetable oil and once it's full continue to fill the larger one with the overflow. The smaller (inner) jar will become invisible, to the naked eye.

On a more serious note this seems to be a big problem with all invisibility cloaks, of non supernatural origin (calm down HP fans), and that is they are all based upon modifying materials refractive index and thus bending the light around the object you want to hide.

That all sounds good but if you could do this to hide an object; If that object were a person since light doesn't hit them, or their eyes, not only would they be invisible but they would also be blind. I think most people asking Santa for a invisibility cloak would like to actually see what's in the girls locker room right?

A perfect invisibility cloak would change the person wearing it, along with the cloak, to a refractive index of air but again, they would be perfectly blinded by the process. In the case of RI = air then the light would go straight through them, included their eyes. So you either bend the light or have it go through your eyes and either way your in the dark.

I guess you could hide everything but your pupils, but in my book you wouldn't be invisible then, floating eyeball freak!